This proposal outlines our plans to further develop and validate new methodologies in the acquisition and processing of digital two dimensional echocardiographic data. Noninvasive two dimensional echocardiography (2D echo) has important potential in the comprehensive characterization of left ventricular structure and function. The deficiency to date has been the imprecise quantification of performance parameters because of limitations in image acquisition, border recognition and image processing in these inherently noisy images. In this proposal, we plan to address this problem in a multidisciplinary, systematic fashion by developing and improving our steps of data acquisition and processing. We will use a commercially available ultrasound unit and the 2D echo data will be directly digitized for image processing. We will develop algorithms for recognition of endocardial and epicardial boundaries and use timevarying image analysis to track these edges thoughout the cardiac cycle. We will employ parametric shape descriptors and shape change models to measure left ventricular function. We will validate the resulting data by comparing them to those obtained in well characterized static phantoms and through direct measurement of cardiac volume throughout the cardiac cycle, utilizing an isolated beating heart preparation. We will also examine the accuracy of our automated approach in determining wall thickness. In addition, by comparing normal and abnormal beating hearts, we hope to identify new indices of cardiac performance. The ultrasound acquisition and processing methods describe in this proposal will have direct application to the study of the intact animal heart and to man. Moreover the isolated heart preparation will allow us to make further observations regarding three dimensinal geometry throughout the cardiac cycle. The development of quantitative 2D echo will have direct impact in the understanding of the dynamic structure and function of the beating heart.